1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a wire grid polarizer and a method of fabricating the same, and more particularly, to a wire grid polarizer having a double layer structure in which two metallic wire layers have a two-layer shape, and a method of fabricating the same.
2. Description of the Related Art
Image forming apparatuses which require an additional light source, such as a liquid crystal display (LCD) or a beam projector, use a polarizer to form an image by variably transmitting or blocking light. However, since conventional polarizers are mainly absorptive polarizers, only half of the light emitted from a light source is used, and the other half is absorbed by the polarizer. Thus, the light use efficiency is low and the brightness is limited.
To avoid these problems, reflective polarizers have been suggested. Reflective polarizers reflect rather than absorb the unused light. An example of a reflective polarizer is a wire grid polarizer. FIGS. 1A and 1B are a cross-sectional view and a plan view, respectively, of a wire grid polarizer 10. As illustrated in FIGS. 1A and 1B, the wire grid polarizer 10 includes a plurality of conductive metallic wires 12 arranged in parallel on a transparent substrate 11 at a regular period. When the period of the metallic wires 12 is similar to or larger than the wavelength of an incident electromagnetic wave, traditional diffraction occurs. However, when the period of the metallic wires 12 is much smaller than the wavelength of the incident electromagnetic wave, diffraction does not occur. In this case, light polarized parallel to the metallic wires 12 (S-polarized light) is reflected, and light polarized perpendicular to the metallic wires 12 (P-polarized light) is transmitted. The width, thickness, and period of the metallic wires 12 determine the polarization characteristics of the wire grid polarizer 10, such as its transmissivity and reflectivity.
However, in order to allow the wire grid polarizer 10 to operate over the entire region of visible rays without loss, the period of the metallic wires 12 must be less than about 100 nm. Such a short period can only be achieved by technology such as laser lithography, electron beam lithography, or nano imprinting, as used in semiconductor fabrication. However, although such technology has been used to develop and produce a wire grid polarizer, the minimum period has been about 150 nm. Furthermore, no technology exists for mass producing a large-scale wire grid polarizer for an image forming apparatus.